The invention relates to a string portion or a string of substantially uniform diameter for stringing a racket for ball games, in particular a tennis racket.
Ball rackets, in particular tennis rackets, are strung with strings in order to provide a resilient striking surface from which a ball impacting thereon can fly off. A simple test demonstrates that the bell rebounds from such a surface higher or faster than from a rigid surface, for example a concrete wall or the like. Even if the striking surface of a ball racket may be of all possible geometrical shapes, nonetheless the predominant proportion of commercially available ball rackets are of a more or less oval striking surface shape; that configuration has proven itself to be the best, over the centuries.
If the ball hits approximately the middle of the oval, or even hits the string bed somewhat more towards the handle, the ball is accelerated back; the ball has hit the so-called "sweet spot", that is to say the best possible acceleration surface on the racket.
The string portions used for conventional stringing arrangements, comprising longitudinal and transverse strings or diagonal strings, are of uniform thickness or are of invariable cross-section. In addition, they are of one material or the same material composition throughout and they are of the same nature within the string. That means that their resiliency characteristics, assuming the same force acting thereon, are the same in every part of the string.
In consideration of those facts, the inventor set himself the aim of enlarging the sweet spot of the striking surface and thus providing ideal stringing against which the ball does not absolutely have to impinge at the middle thereof in order to enjoy optimum acceleration. In spite of a very high level of skill on the part of a player, the certainty of hitting the ball at the middle of the racket is not always possible. The invention also seeks to provide generally improved hitting characteristics of the racket.
Further objects and advantages of the present invention will appear below.